Machine tools are used for a variety of machining operations, such as milling, drilling, boring, and reaming. Different types of cutting devices are rotatably mounted to such machine tools via an appropriate attachment device, such as a chuck. The cutting device is then rotated as it is moved into a material undergoing a machining operation. For example, a cutting device designed for milling can be attached to a machine tool and used to cut metal from a workpiece.
Cutting devices typically include a tool body or cutter body attached to a shank designed to be held by the machine tool. Generally, a plurality of cutter inserts will be mounted longitudinally along the exterior of the cutter body. A nosepiece is either integrally formed with the cutter body or constructed as a separate component. The nosepiece is critical since it is usually the portion of the cutting device which initiates the cutting of the material. Often, it is desirable to make nosepieces interchangeable so that different nosepieces may be attached to the cutter body for specific cutting operations or when the cutter inserts become dull or worn.
Some current interchangeable nosepieces have a center bore extending longitudinally therethrough. This type of nosepiece is keyed to the cutter body to prevent rotation of the nosepiece with respect to the cutter body. Existing cutter bodies also include a longitudinal threaded bore to receive a retaining bolt which holds the nosepiece to the cutter body. Although this arrangement works well for many machining operations, the retainer bolt does not allow placement of cutter inserts placed centrally in the front face of the nosepiece (i.e. the face generally perpendicular to the axis of rotation of the nosepiece). As a result, such nosepieces are able to machine the side of a workpiece, but they are not capable of effectively drilling due to the absence of cutting inserts at the front face of the nosepiece.
As five-axis and six-axis machine tools become more common, cutting devices with the ability to cut both at the front face and along the edge are important to take advantage of the added efficiencies of such multi-axis equipment. For example, in certain machine tool operations, such as the cutting of dies, it is often desirable to move the cutter straight into the material and then rotate it or move it in various other directions to form the specific contours of the desired die. To do this quickly and efficiently, it is desirable to have a cutting device with a front face having a relatively large diameter, and cutting inserts located on the front face and the circumferential surface of the device.
Currently, the above-described operations are primarily accomplished with either a ball nose cutter or a cutting device having an integral cutter body and nosepiece. There has not been a satisfactory way of making interchangeable nosepieces with center cutting capability. Ball nose cutters are older style cutters having two flutes and a rounded nosepiece for cutting. One problem with such cutters is the relatively small area of cutting at the front of the tool. With such a cutter, the milling of a die, for instance, requires numerous passes to achieve the desired die contour.
In the alternative, cutters have been designed with a wider frontal face and centrally located cutter inserts to cut a wider diameter path at each pass of the cutting device. As mentioned above, however, these devices tend to have the cutter body and nose piece formed as a single unit. This can have many disadvantages. For instance, if a die manufacturer is currently using cutter devices with removable nosepieces but plans to convert to five and six axis machine tools, that manufacturer would need to replace its existing nosepieces and cutter bodies. This would make the conversion to multiple axis machinery more expensive. Additionally, every time a different machining operation required a different nosepiece, the entire cutter body and nosepiece configuration would need to be replaced.
It would be advantageous if the nosepieces could be interchanged rather than interchanging the entire cutter body. Then, if a different machining operation were required or if the cutter inserts on the nosepiece became worn, a different nosepiece could be attached to the cutter body with minimal down time. Also, since many fabricators and manufacturers already use cutter bodies designed for use with conventional removable nosepieces, it would be beneficial to provide center and side cutting nosepieces that could be used with such existing cutter bodies.